Apparatus for connecting flanged pipes

ABSTRACT

An apparatus for connecting two flanged pipes comprises at least one piston arrangement having a pair of opposed pistons slidable within a hydraulic cylinder. Each pair of pistons has a rod extending therefrom and is adapted to receive a threaded fastener at its end remote from the piston. Each rod extends through an aperture at the respective cylinder end and is adapted to pass through a respective aperture in the flange of a flanged pipe. Each piston has an associated biasing means in the form of a spring or similar which urges the piston away from its respective cylinder end. Pressurization of the hydraulic fluid in the cylinder causes the piston to move towards its respective cylinder end against the urging action of the biasing means, to allow the hand tightening of the threaded fastener. When the pressure is removed the action of the spring biases the flanges of the flanged pipes together to energize the ring seal between each flange and the apparatus.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus for connecting flanged pipes,particularly large diameter flanged pipes which in use are subject tohigh pressure such as risers in oil-field applications.

It is a well-known requirement that shorter sections of pipe such asriser sections must be joined together to form longer pipes or risers.Such pipe sections are provided in standard lengths and delivered to thelocation in which the pipe is to be installed. Each section has acircular flange at each end, each flange being provided with a number ofapertures and a circumferential groove in the mating surface of theflange, in which may be placed a ring seal. Two pipe sections arebrought together such that the mating surfaces are aligned with a ringseal between them. Threaded fasteners or bolts are placed in theapertures and nuts are tightened onto the bolts. The nuts are tightenedto a predetermined torque in order to energise the ring seal.

The known method of joining flanged riser sections suffers from thedisadvantage that it is slow and difficult to carry out under adverseconditions. The method requires considerable strength, skill andreliability of operators, together with the use of heavy tools inconfined spaces or areas of difficult access. Furthermore, the securingforce is dependent on the extent of wear and the general condition ofthe threaded fasteners.

JP 0800-11063 discloses an auxiliary device for tightening the nuts andbolts that fasten the flanges of pipe sections. A piston portion of thedevice is attached to each of the bolts and hydraulic pressure isapplied to the piston head which draws each bolt towards the deviceallowing the associated nut to be manually tightened. However, time andeffort is required to attach each piston portion of the device to, andremove the portion from, each individual bolt for tightening theassociated nut.

According to a first aspect of the invention, there is provided anapparatus for connecting two flanged pipes comprising at least onepiston arrangement having a pair of opposed pistons slidable within ahydraulic cylinder,

-   -   each of said pair of pistons having a rod extending therefrom        and adapted to receive a fastener at its end remote from the        piston,    -   each of said rods extending through an aperture at the        respective cylinder end and being adapted to pass through a        respective aperture in the flange of a flanged pipe,    -   each of said pistons having an associated biasing means which        urges the piston away from its respective cylinder end,    -   wherein pressurisation of hydraulic fluid in the cylinder causes        the piston to move towards its respective cylinder end against        the urging action of the biasing means.

In use the apparatus may be placed between two flanged pipes such thatthe two opposing rods of the piston arrangement extend through therespective apertures in the flanges of the two flanged pipes. Nuts aresecured to threaded ends of the rods, so that the apparatus is securelyheld between the two flanged pipes. When the hydraulic fluid ispressurised the pistons are forced against the biasing action so thatthe rods and nuts move outwards. The nuts may then be further tightenedonto the threaded ends of the rods. When the pressure in the hydraulicfluid is removed the biasing means urges the pistons towards each other,so energising the connection between each flanged pipe and theapparatus.

Preferably the fastener is a threaded fastener. Preferably, theapparatus comprises a cylindrical body. Preferably, the cylindrical bodyhas an axial through bore. This bore is preferably the same size as theinternal bore of the two pipe sections to be joined. When the apparatusis used to join two pipe sections, the axial through bore is alignedwith the internal bore of each of the pipe sections.

Preferably, the apparatus comprises a plurality of said pistonarrangements spaced at intervals about and externally of the throughbore. Preferably, there are four or more piston arrangements spacedequidistantly on a circumference. Preferably, the piston arrangementsare arranged such that the pistons move parallel to the axis of thethrough bore. A standard flange has 12 apertures, so the apparatus forjoining pipes having such flanges would have 12 piston arrangementsarranged at the same relative positions as the 12 apertures.

Preferably, each of the biasing means comprises a spring. The spring maybe arranged around the rod and may act between the piston and therespective end wall of the cylinder. Typically the spring comprises anumber of conical washers, although a helical spring of appropriatestiffness may be used.

Preferably, hydraulic fluid is provided between the pistons in thecylinder. Preferably, the apparatus comprises one or more hydraulicfluid passages communicating with the one or more hydraulic cylinders ata connection point in each of the cylinders arranged between the twopistons.

Preferably the apparatus comprises first and second bearing faces atopposite ends adapted to bear in use against the end faces of the pipesto be joined. Preferably each of the bearing faces is provided with acircumferential groove adapted to house a ring seal.

According to a second aspect of the invention, there is provided a pipeconnection comprising a first pipe having a first flange at the endthereof, a second pipe having a second flange at the end thereof, and anapparatus according to the first aspect of the present invention.

Preferably, the two opposing rods of the piston arrangement extendthrough respective apertures in the flanges of the two pipes.

Preferably, the pipe connection further comprises a threaded fastenersecured to the end of each of the rods. Preferably, the end of each rodis provided with an external thread and the threaded fastener is a nut.

Preferably, the number of piston arrangements is equal to the number ofapertures in each flange.

According to a third aspect of the invention, there is provided a methodfor connecting first and second flanged pipes, the method comprising thesteps of:

-   -   (a) providing an apparatus comprising at least one piston        arrangement having first and second opposed pistons slidable        within a hydraulic cylinder, each of said first and second        pistons having a rod extending therefrom and having associated        biasing means adapted to bias the piston away from the end of        the cylinder;    -   (b) placing the apparatus between the opposing flanges of the        flanged pipes such that the rod of the first piston projects        through an aperture in the flange of the first pipe and the rod        of the second piston projects through an aperture in the flange        of the second pipe;    -   (c) securing a fastener to each of the rods and tightening the        fastener against the respective flange;    -   (d) pressurising the cylinder between the pistons to cause the        pistons and rods to move away from each other and to cause the        fasteners to move away from the respective flanges;    -   (e) tightening further each fastener against the respective        flange; and    -   (f) reducing the pressure in the cylinder to cause the pistons        and rods to move towards each other under the action of the        biasing means and to cause the fasteners to apply a greater        clamping force to the respective flanges.

Preferably the or each fastener is a threaded fastener.

Steps (d) to (f) may be repeated as required, particularly in the casewhen a seal ring is provided between the apparatus and each of theflanges, and the seal ring deforms plastically under the action of theincreased clamping force.

The method may further include the step of measurement of the clampingforce. The force may be measured using at least one tension indicatorconnected to the or each fastener. Alternatively, the force may bemeasured using at least one load washer.

Preferably the apparatus is an apparatus according to the first aspectof the invention.

According to a fourth aspect of the invention, there is provided anapparatus for connecting a first pipe having a flange and a second pipecomprising at least one piston arrangement having a piston slidablewithin a hydraulic cylinder,

-   -   the piston having a rod extending therefrom and adapted to        receive a fastener at its end remote from the piston,    -   said rod extending through an aperture at the respective        cylinder end and being adapted to pass through a respective        aperture in the flange of the first flanged pipe,    -   said piston having an associated biasing means which urges the        piston away from its respective cylinder end,    -   wherein pressurisation of hydraulic fluid in the cylinder causes        the piston to move towards its respective cylinder end against        the urging action of the biasing means.

Preferably the apparatus further comprises a flange remote from said rodfor abutting a flange provided on the second flanged pipe. Preferablythe flange of the apparatus has at least one aperture for receiving oneor more fasteners. Alternatively the apparatus further comprises a weldneck remote from said rod for welding of the apparatus to the secondflanged pipe. Alternatively the apparatus forms an integral part of theinlet of an item of equipment.

According to a fifth aspect of the invention, there is provided a methodfor connecting a first pipe having a flange and a second pipe, themethod comprising the steps of:

-   -   (a) providing an apparatus comprising at least one piston        arrangement having a piston slidable within a hydraulic        cylinder, said piston having a rod extending therefrom and        having associated biasing means adapted to bias the piston away        from the end of the cylinder;    -   (b) placing the apparatus between the pipes such that the rod of        the piston projects through an aperture in the flange of the        first pipe;    -   (c) securing a fastener to the or each rod and tightening the        fastener against the flange of the first pipe;    -   (d) pressurising the cylinder between the or each piston to        cause the or each piston and rod to move away from each other        and to cause the or each fastener to move away from the flange        of the first pipe;    -   (e) tightening further the or each fastener against the flange        of the first pipe; and    -   (f) reducing the pressure in the cylinder to cause the or each        piston and rod to move towards each other under the action of        the biasing means and to cause the or each fastener to apply a        greater clamping force to the flange of the first pipe.

Preferably the apparatus further comprises a flange remote from said rodand having at least one aperture, the second pipe is provided with aflange having at least one aperture, and the method further comprisesthe step of locating a bolt through the or each aperture of the flangeof the apparatus and the or each aperture of the flange of the secondpipe, securing a fastener to the or each bolt and tightening the or eachfastener.

Alternatively the apparatus further comprises a weld neck remote fromsaid rod, and the method further comprises the step of welding theapparatus to the second pipe.

Example embodiments of the invention will now be described by wayexample only, with reference to the accompanying Figures, in which:—

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a connecting apparatus according to thefirst aspect of the present invention;

FIG. 2 is an enlarged sectional view of a piston of the connectingapparatus of FIG. 1;

FIG. 3 is a plan view on the apparatus of FIG. 1 with the flange of thepipe and the ring seal omitted for clarity; and

FIG. 4 is a sectional view of a connecting apparatus according to thefourth aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A connecting apparatus generally described at 1 comprises a cylindricalbody 2 having an axial through bore 3. The apparatus is shown in theunenergised state between the first flange 20 of a first pipe 10 and thesecond flange 22 of a second pipe 12. Between each of the end faces 4, 5of the cylindrical body 2 and the respective end faces 24, 26 of theflanges 20, 22 there is provided a ring seal 30 which, in itsunenergized state, stands proud of the circular grooves 6, 28 in the endfaces 4, 5, 24, 26 of the cylindrical body 2 and flanges 20, 22, therebycreating a gap between the adjacent faces 4, 5, 24, 26 of thecylindrical body 2 and flanges 20, 22.

In order to prevent the existence of this gap, and to provide aneffective seal between the flanges 20, 22 and the cylindrical body 2, itis necessary to forcibly push the flanges 20, 22 against the cylindricalbody 2. This is achieved by the piston arrangements generally indicatedat 50. The effect of compressing the flanges 20, 22 against thecylindrical body 2 is to energise or compress the seal 30. Thiscompression is desirable to increase the effectiveness and efficiency ofthe seal 30.

Each piston arrangement 50 includes a cylinder 52 adapted to house anopposed pair of slidable pistons 54, 56, a plug 58 closing each end ofthe cylinder 52 and clamping springs 60. The pistons are provided withpiston rings 72 which seal between the pistons 54, 56 and the cylinder52. The springs 60 serve to bias the pistons away from the plugs 58 atthe ends of the cylinder 52. Each piston 54, 56 is provided with anintegral rod 64, 66 which extends through an aperture in the plug 58sealed with an O-seal 62. The springs 60 are provided around the rods64, 66 and act between the plugs 58 and the piston bodies 54, 56. Therod 64, 66 is provided with an externally threaded portion 68 at itsfree end, adapted to receive an internally threaded nut 70.

The rod 64, 66 passes through an aperture 32, 34 provided in therespective flange 20, 22. A washer 74 is provided between the nut 70 andthe flange 20, 22. One or more dowels (not shown) engage both the piston54, 56 and the cylinder 52 in each arrangement for the purpose ofpreventing rotation of the piston 54, 56 when the nut 70 is tightened.

In the embodiment shown, there are provided 12 piston arrangements 50arranged equidistantly on a circumference whose radius corresponds tothe radius of the circumference in which the apertures 32, 34 in theflanges are arranged. The piston arrangements are permanently secured tothe cylindrical body 2, although the nuts 70 are detachable, therebyallowing removal of the flanges 20, 22 from the connecting apparatus 1.

A hydraulic hose connection 80 is provided at the edge of thecylindrical body 2. A network of hydraulic fluid passages 82 links theconnection 80 to the central portion of each of the cylinders 52 of thepiston arrangements 50. These passages 82 are formed by drilling andthen plugging the ends 84, so that the passages 82 do not communicatewith the exterior except through the hose connection 80.

The connecting apparatus 1 can be used to connect any flanged pipes, butit is particularly appropriate for use with 7 1/16″ snubbing risersections, when a number of flanged connections (typically 10 to 15) needto be made up in as short a time as possible in order for the snubbingor oil drilling rig to be able to start its drilling operation. Duringassembly the individual lengths of riser must be connected at a locationabove the rig floor which is difficult to access.

In use, a connecting apparatus 1 is provided which has an internal bore3 equal in size to the bore of the pipe sections 10, 12 to be joined.The upper and lower faces 4, 5 of the apparatus have gasket or ring sealarrangements which match those on the flanges 20, 22 of the pipesections 10, 12 to be joined. The apparatus 1 has a number of threadedconnecting rods 64, 66 protruding from each face 4, 5 and these areengaged with corresponding apertures 32, 34 in the flanges 20, 22. Thethreaded connecting rods 64, 66 are equal in number, length and diameterto the threaded connectors used to join conventionally the pipe sections10, 12.

Once the apparatus 1 is in place between the opposing flanges 20, 22 ofthe flanged pipes such that the rods 64 on the upper side projectthrough the apertures 32 in the flange 20 of the upper pipe 10 and therods 66 on the lower side project through the apertures 34 in the flange22 of the lower pipe 12, a threaded fastener or nut 70 is secured toeach of the rods 64, 66 and the fastener 70 is tightened against therespective flange 20, 22. It is only necessary to tighten the nuts 70 byhand or to a low torque at this stage, sufficient to cause the nuts 70to bed down.

The following sequence of events is then followed:

-   1. The cylinders 52 are hydraulically pressurised between the    pistons 54, 56 to cause the pistons 54, 56 and rods 64, 66 to move    away from each other thereby compressing the springs 60 and causing    the threaded fasteners 70 to move away from the respective flanges    20, 22;-   2. Each fastener 70 is tightened further against the respective    flange 20, 22 (again low torque or hand tightening is appropriate);-   3. The pressure in the cylinders 52 is reduced to cause the pistons    54, 56 and rods 64, 66 to move towards each other under the action    of the springs 60 which serve as biasing means and to cause the    threaded fasteners to apply a greater clamping force to the    respective flanges.

Steps 1 to 3 above may be repeated as required, until the requiredclamping force is achieved, so that the tension in the rods 64, 66 isequal to the tension exerted on the equivalent studs of a standardthreaded stud connection by tightening them to their recommended torque.Therefore, should the connecting apparatus 1 fail for any reason, thefasteners 70 can be removed using conventional tools.

When a seal ring 30 is provided between the apparatus 1 and each of theflanges 20, 22, repetition of steps 1 to 3 may be necessary, since theseal ring 30 deforms plastically under the action of the increasedclamping force, to form a seal against the inclined sides of the sealgroove 6.

Measurement of the clamping force can be performed, in order to verifythe clamping force provided by each piston arrangement 50. To measurethe force, a number of tension indicators (not shown) can be connectedto the fastener 70 in a manner known in the art. Alternatively, theforce may be measured using one or more conventional load washers (notshown).

FIG. 4 shows a second embodiment of the present invention. The apparatusis identical to that of the first embodiment above the line A—A shown inthe figure, and identical elements will not be described.

In this embodiment, the connecting apparatus 1 comprises only one piston54 within each piston arrangement 50. The cylinder 52 is blanked off atthe head end 55. Thus, when the cylinders are pressurised via thehydraulic connection 80, the hydraulic pressure will act only on onepiston head 54 for each piston arrangement 50.

Connection to a first pipe, using the piston arrangements 50, is thesame as described above. The apparatus also comprises a conventionalflange 57 with apertures 59 for connecting the apparatus 1 to the flange22 of the second pipe 12. The two flanges 22, 57 may be joined togetherusing any conventional means such as nuts 70 and bolts 65.

While the embodiment of FIG. 4 includes a conventional flange 57 andnuts 70 and bolts 65, the connecting apparatus 1 may be connected to thesecond pipe 12 in other ways known in the art. For instance, theapparatus may be provided with a weld neck (not shown), allowing weldingof the apparatus 1 to the second pipe 12. Typically, the second pipewould not require a flange 22 and the weld neck would be sized to fitaround the outer diameter of the pipe 12. The apparatus 1 could then beseam welded to the pipe 12. In another alternative, a manufacturer mayprovide the apparatus 1 comprising a single piston 54 for each pistonarrangement 50 at the inlet of an item of equipment.

The embodiment of the invention comprising a single piston 54 for eachpiston arrangement 50 can allow the apparatus 1 to be permanentlyattached to a pipe or item of equipment.

Referring now to either embodiment of the invention, it should be notedthat the piston arrangement 50 of the apparatus and method describedherein allows the nuts 70 to be tightened by hand and does not require alarge torque. It will be appreciated that this is a considerableadvantage over the requirement of using heavy tools which has been thepractice in the past. Such tools include conventional wrenches andtorquing devices, flogging wrenches and sledge hammers.

The invention permits greater repeatability and reliability ofconnections, since the hydraulic pressure to which the pistons 54, 56are subjected may be monitored. Typically a pressure of between 10,000and 20,000 psi may be achieved. Furthermore, the need for intensivemanual or skilled labour by operators is also mitigated. Similarly,there is a reduced danger of injury to operators or bystanders duringsuch operational and maintenance functions.

A further advantage of the invention is that the clamping pressure maybe predetermined by the springs and it is possible to achieve uniformpressure around the periphery of the liner, which enables perfect lineralignment.

Other advantages of the invention will become apparent to operators andassociated personnel involved in the implementation and operation of theinvention, including the fact that reduced time is required to affectthe connection of the pipes.

Further modifications and improvements may be incorporated withoutdeparting from the scope of the invention.

1. An apparatus for connecting two flanged pipes comprising at least onepiston arrangement having a pair of opposed pistons slidable within ahydraulic cylinder, each of said pair of pistons having a rod extendingtherefrom, said rod having a remote end remote from the piston and beingprovided with a removable fastener at said remote end, each of said rodsextending through an aperture at the respective cylinder end and beingadapted to pass through a respective aperture in the flange of a flangedpipe, each of said pistons having an associated biasing means whichurges the piston away from the respective cylinder end, whereinpressurization of hydraulic fluid in the cylinder causes the piston tomove towards the respective cylinder end against the urging action ofthe biasing means.
 2. An apparatus according to claim 1, wherein theremote end of the rod has a threaded outer surface and the removablefastener is a threaded fastener.
 3. An apparatus according to claim 1,comprising a cylindrical body having an axial through bore.
 4. Anapparatus according to claim 3, comprising a plurality of said pistonarrangements spaced at intervals about and externally of the throughbore.
 5. An apparatus according to claim 1, wherein each of the biasingmeans comprises a spring arranged around the rod.
 6. An apparatusaccording to claim 1, further comprising one or more hydraulic fluidpassages communicating with the one or more hydraulic cylinders at aconnection point in each of the cylinders arranged between the twopistons.
 7. An apparatus according to claim 1, further comprising firstand second bearing faces at opposite ends adapted to bear in use againstthe end faces of the pipes to be joined, each of the bearing faces beingprovided with a circumferential groove adapted to house a ring seal. 8.A pipe connection comprising a first pipe having a first flange at theend thereof, a second pipe having a second flange at the end thereof,and an apparatus according to claim 1, wherein the two opposing rods ofthe one or more piston arrangements extend through respective aperturesin the flanges of the two pipes.
 9. A pipe connection according to claim8, wherein the number of piston arrangements is equal to the number ofapertures in each flange.
 10. A method for connecting first and secondflanged pipes having opposing flanges, the method comprising the stepsof: (a) providing an apparatus comprising at least one pistonarrangement having first and second opposed pistons slidable within ahydraulic cylinder, each of said first and second pistons having a rodextending therefrom and having associated biasing means adapted to biasthe piston away from the end of the cylinder; (b) placing the apparatusbetween the opposing flanges of the flanged pipes such that the rod ofthe first piston projects through an aperture in the flange of the firstpipe and the rod of the second piston projects through an aperture inthe flange of the second pipe; (c) securing a fastener to each of therods and tightening the fastener against the respective flange; (d)pressurizing the cylinder between the pistons to cause the pistons androds to move away from each other and to cause the fasteners to moveaway from the respective flanges; (e) tightening further each fasteneragainst the respective flange; and (f) reducing the pressure in thecylinder to cause the pistons and rods to move towards each other underthe action of the biasing means and to cause the fasteners to apply agreater clamping force to the respective flanges.
 11. A method accordingto claim 10 wherein steps (d) to (f) are repeated.
 12. A methodaccording to claim 10 further comprising the step of measuring theclamping force applied by at least one fastener.
 13. An apparatus forconnecting a first pipe having a flange and a second pipe, the apparatuscomprising at least one piston arrangement having a piston slidablewithin a hydraulic cylinder, the piston having a rod extendingtherefrom, said rod having a remote end remote from the piston and beingprovided with a fastener at said remote end, said rod extending throughan aperture at the respective cylinder end and being adapted to passthrough a respective aperture in the flange of the first flanged pipe,said piston having an associated biasing means which urges the pistonaway from its respective cylinder end, wherein pressurization ofhydraulic fluid in the cylinder causes the piston to move towards itsrespective cylinder end against the urging action of the biasing means.14. An apparatus according to claim 13, further comprising a flangeremote from said rod for abutting a flange provided on the second pipe,and wherein the flange of the apparatus has at least one aperture forreceiving one or more fasteners.
 15. An apparatus according to claim 13,wherein the second pipe is the inlet of an item of equipment.
 16. Amethod for connecting a first pipe having a flange and a second pipe,the method comprising the steps of: (a) providing an apparatuscomprising at least one piston arrangement having a piston slidablewithin a hydraulic cylinder, said piston having a rod extendingtherefrom and having associated biasing means adapted to bias the pistonaway from the end of the cylinder; (b) placing the apparatus between thepipes such that the rod of the piston projects through an aperture inthe flange of the first pipe; (c) securing a fastener to the or each rodand tightening the fastener against the flange of the first pipe; (d)pressurizing the cylinder between the piston and the second end of thecylinder to cause the piston and rod to move away from the second endand to cause the fastener to move away from the flange of the firstpipe; (e) tightening further the fastener against the flange of thefirst pipe; and (f) reducing the pressure in the cylinder to cause thepiston and rod to move towards the second end under the action of thebiasing means and to cause the fastener to apply a greater clampingforce to the flange of the first pipe.
 17. A method according to claim16, wherein the apparatus further comprises a flange remote from saidrod and having at least one aperture, the second pipe is provided with aflange having at least one aperture, and the method further comprisesthe step of locating a bolt through the or each aperture of the flangeof the apparatus and the or each aperture of the flange of the secondpipe, securing a fastener to the or each bolt and tightening the or eachfastener.